Electric furnace.



J. THOMSON.

ELECTRIC FURNACE.

APPLICATION FILED SEPT. 1, 1909.

994,217, Patented June 6,1911

C/g vd. -lqvent0r:

NITED, s'm'ins JOHN THOMSON,

flffl i' OFFICE ELECTRIC FURNACE,

Application filed September 1, 130% Serial No. 515,?00.

To all whom it may concern:

Be it known that-I, Jon .l1-1oirso1-:., u citizen of the United Status and u rosidoui' of the borough of; Manhattan. of the city oi j 5 New York, in the county and State; of New E York, have inventml certain now and useful Improvements in Elomrio llurusoos, of l whlch the following :1 s woificutiom vefsr once being had to the accompanying draw-- ins, forming a parthereof'. l

his invention relates to improvermt-nls in electric furnaces-of the type in which hoot; generated by passing the current llllmig'li resistor ordinarily formed of carbon.

The general obj out of the improvements is to provide a furnace (ifthis typo in Wlllffll the thermal loss clue to rudiotiou shall little as possible; and in uooonilzmco 1- the improvements he rosisli'ur arrange u as to be either partially or wholly immerse:

in the both, In order that the, resistor may b' electrified, while thus partially or wlmlly 1 surrounded by the material to he heated, a casing or shield is provided to envelop 11m resistor aml thus prevent the bath from mum-- in oontuut with it, ll}; this means tom the rosistop is proteofezi from the ollvnts ol the oxygen and other uotivo coustihwnis of p the gases of the melting olmmlaozg this in foot being another object which UH, lam-mtion is designed to affect A convenient ancl practical (cuilieullmoiu, 0f f'ho invention is lllllSifld (l in ills fumimn shown in lhe acooznpszlyuigzg tirawlrugsy ii;-

which,

' Figure l is a top plum "viow of said furuzwo with the mower romovocl, showing a 'porl'iou of the interior in horizonlal section, mull,

' Fig. 2' is a transverse contra? suction of Fig.

40 1, the cover l ming; in this immune, hull-outed by tho-broken lines, as'H.

The brick casing a is provided with a. rofractory lining a to form the nzel 11g chum her 0 across which the resistor 2: ends. in

the present case, the resistor is oomprissd of two main sections, l) onrl IX, each suction having a pair'of limiting liemliuols o and e, whereby the two sections may loo electrified separately or in parallel or, as iilus trated in the present case, connected up "in series by havingtho lorminals a jfllnflfil' by the" 'oonnector piece (1 and this tenninals a connected to ,an oleotriobimuit shown Tho terminals 6 are arranged to he sli cluhle and bolts and nuts of are il l'fivl lled :Eox" im- Espoclfication 01' I wwrs Palm-b. ,Pa'zbontoi'l J one 6,1911.

puriing, tlmfvugh llil l connector piece 6, the mr uirol m'm'mnr', of 'endtlnrust upon the im'u'wim'lls e for ELIJHIPOSQ presently to be oxplziinol 'Eho KQElS IOI so for us tho'prcsent invenlion ooi'looz'ncd, may be constructed in various in the present case, each seclion film}: is built by aggregating a pin l ivixluul members (.Z, the opposing sons of Wi'lhtll 2!!(5' formed so as to iutorlmzk W. h ouch other, whereby under a suitable i along earl: suction, iho g rival in a 1i moi, line Without any om'z'aiuzm s moons of support exoopt all also im'minuls. 'llz-s gglol'nils of oonstrucis of such a rosistor and lon'ninuls are more par fin in .Leitovs Patent No. 153M), filed Fluptonv 1 will, lliorofore, be 1mnm sszuy to zep'ont (hut description hero. l l; section of "he i-osisfor suspended well down in the u'iolting chamber and is pl'ovidodwillz moons to shield it from confuol'. with Hue, hulls, such shield being profer- Kalil}; in Hal: form of u refractory Casing 0* Lu in tho mouse Walls at nunll curl and surrounding or m'oloping that of lhe resistor which would. other- W901i to {he melting; nhambor. j l'aowmor has no physicalconu l; film rosislm: but, on tho othr hand, 0 v' a slow space as shown in Fig. 2 of um (low in mn liotwoou tho inner surface of la ill 31 of the casing and tho exterior I i ,w oom'ospomling portions of the i-osisi'm' and the, oonlzwuous parts of the terminals- 'wl'iiclx the casinos encompass. The uasngs are thus oleciricully insulated l) spoo from he resistor. Moreover, the ems of the casings ans preferably left open so asio be free for the terminals to extend tlui'mgh, and Where the ends rest in the re {factory lining c of the-melting chamber, filmy ui o lutod or built, intothe lining, as at 0K Fig. 1. in. orclor to prevent leakage of fiuioi metal around said onds.

Manifostl by the foregoing construction,

. tho resistor may ho so disposed that the bath units in the shortest period of time.

Before applying current to the resistor, the space between it and its'casing may be filled, if desired, and so maintained, withan inert gas, displacing air and its contained oxygen; but no claim of invention is made herein to the surroundingof the resistor with an inert gas. 4

The material of which the casings are formed may be that best adapted for with standing the action of the substance with which the casings are in contact. Ordinarily fire clay, crucible mixtures, that is, combinations of graphite and clay, and recrystallized silicon carbid would be used. The peculiarly favorable features of the last named material are set forth in an earlier application for Letters Patent, filed May. 13, 1909, Serial No. 495,585. But in any instance, the electrical conductivity of the easing-material needs not to be considered. in that it is insulated from the resistor and its terminals by space. Again, as the casing is subjected almost entirely to compressive strains, the extent of which is limited by the depth of its immersion and the density of the fluid, its wall. may be made about as thin as can readily be molded. To relieve the casing of transverse strains, it may be supported by refractory props and confined 'against flotation stresses by the parts 0 In manymet-allurgical operations this furnace may berun continuously, as once the bath is established the ore or metal can be readily fed, say through openings in the cover, and the accumulated residue can be drawn off through suitable taps (not shown VVith respect to the resistor and its casings, it will be apparent that the effect of slags, pernicious gases, oxygen or the atmospheres of various metallic vapors is eliminated from the problem on account of the inclosing of the resistor, and need not be considered. Any temperature Within the range of usual commercial requirements can be obtained and uniformly maintained, and the thermal loss due to radiation will be the least possible, in any like instance of heat insulation, in that no part of the melting chamber can be hotter than, or as hot as, the bath. itself' And while the resistor and its casings are shown in the drawings as being completely immersed, it is pointed (at that if for any purpose it should be desirable, they may readily-be partially withdrawn thereby acting upon the bath bya combination of direct heat-conduction below and reverberation from the cover above. Moreover, this system lends itself equally well to forms of furnaces other than that denoted in the drawings, such say, as the oscillatory and rotary types.

I claim as my invention:

1. An electric furnace having a melting chamber provided with a refractory lining, a'resistor the lower part ofwhich is lower than the top of the lining and.a casing extending around the lower part of the resistor to protect it from the molten metal in said chamber, there being a freespace between the casing and the resistor, there sistor comprising interlocked resisting members. v 2. An electric furnace having a melting chamber pro\-'ided with a refractory lining, andan incased resistor, there being a free space between the resistor and its casing and the resistor-"and casing both being located at a lower cleyation than the top of the lining. the resistor comprising interlocked resisting members.

3. An electrlc furnace having an incased resistor which is adapted to be immersed in i a molten bath or charge of material to be resistor which is adapted to be immersed in a molten bath or charge of materialto be melted, said resistor formed of a plurality .of interlocking members operated in series,

and electrically connected outside of the furnace chamber.

6. Aii electric furnace'having a resistor adapted to be immersed-in a molten bath or charge of material to be melted said resistor being formed with a plurality of interlocked.

resisting members arid a casing surrounding said resistor and separated therefrom by a free space, the said resistor being electricallyconnected outside of the furnace chamber and the interlocking members thereof being operated in. series.

This specification signed and witnessed thi 31st day of August, A. 11.1909.

JOHN THOMSON; Signed in the presence of- M. RoLLINs',- G. MCGRANN.

.90 melted, said resistor formed of a plurality of 

